Total knee replacement (also called knee arthroplasty) is a common orthopaedic procedure
that is used to replace the damaged or worn surfaces of the knee. Replacing these
surfaces with an implant or "prosthesis" will relieve pain and increase mobility,
allowing you to return to your normal, everyday activities.

The traditional approach to knee replacement uses a long vertical incision in the
center of the knee to view and access the joint. Minimally invasive total knee replacement
is a variation of this approach. The surgeon uses a shorter incision and a different,
less-invasive technique to expose the joint—with the goal of reducing postoperative
pain and speeding recovery.

Unlike traditional total knee replacement, the minimally invasive technique is not
suitable for all patients. Your orthopaedic surgeon will discuss the different surgical
options with you.

Description

During any knee replacement, the damaged cartilage and bone from the surface of the
knee is removed, along with some soft tissues. The goal of knee replacement surgery
is to provide the patient with a pain-free knee that allows for the return to daily
activities and lasts for a long time.

Minimally invasive knee replacement differs from traditional knee replacement in that
it uses an incision that is approximately half as long and fewer muscles are cut and
detached.

Traditional Knee Replacement

To perform a traditional knee replacement, the surgeon makes an 8- to 10-inch vertical
incision over the front of the knee to expose the joint. The surgeon will then:

Prepare the bone. The damaged cartilage surfaces at the ends of the femur and tibia are removed along
with a small amount of underlying bone.

Position the metal implants. The removed cartilage and bone is replaced with metal components that recreate the
surface of the joint.

Resurface the patella. The undersurface of the patella (kneecap) is cut and resurfaced with a plastic button.
Some surgeons do not resurface the patella, depending on the case.

Insert a spacer. A plastic spacer is inserted between the metal components to create a smooth gliding
surface.

Minimally Invasive Knee Replacement

In minimally invasive knee replacement, the surgical procedure is similar, but there
is less cutting of the tissue surrounding the knee. The artificial implants used are
the same as those used for traditional knee replacement. However, specially designed
surgical instruments are used to prepare the femur and tibia and to place the implants
properly.

Minimally invasive knee replacement is performed through a shorter incision—4 to 6
inches versus 8 to 10 inches for traditional knee replacement. A smaller incision
allows for less tissue disturbance.

In addition to a shorter incision, the technique used to open the knee is less invasive.
In general, techniques used in minimally invasive knee replacement are "quadriceps
sparing," meaning they avoid trauma to the quadriceps tendon and muscles in the front
of the thigh. Other minimally invasive techniques called "midvastus" and "subvastus"
make small incisions in the muscle but are also less invasive than traditional knee
replacement. Because the techniques used to expose the joint involve less disruption
to the muscle, it may lead to less postoperative pain and reduced recovery time.

The hospital stay after minimally invasive surgery is similar in length to the stay
after traditional knee replacement surgery--ranging from 1 to 4 days. Physical rehabilitation
is a critical component of recovery. Your surgeon or a physical therapist will provide
you with specific exercises to help increase your range of motion and restore your
strength.

Minimally invasive total knee replacement is not suitable for all patients. Your doctor
will conduct a thorough evaluation and consider several factors before determining
if the procedure is an option for you.

In general, candidates for minimal incision procedures are thinner, younger, healthier
and more motivated to participate in the rehabilitation process, compared with patients
who undergo the traditional surgery.

Minimally invasive surgeries may be less suitable for patients who are overweight
or who have already undergone other knee surgeries.

In addition, patients who have a significant deformity of the knee, those who are
very muscular, and those with health problems that may slow wound healing may be at
a higher risk for problems from minimally invasive total knee replacement.

Minimally invasive knee replacement is an evolving area and more research is needed
on the long-term function and durability of the implants.

The benefits of minimally invasive knee replacement have been reported to include
less damage to soft tissues, leading to a quicker, less painful recovery and more
rapid return to normal activities. Current evidence suggests that the long-term benefits
of minimally invasive surgery do not differ from those of knee replacement performed
with the traditional approach.

Like all surgery, minimally invasive surgery has a risk of complications. These complications
include nerve and artery injuries, wound healing problems, infection, and errors in
positioning the prosthetic knee implants.

Like traditional knee replacement surgery, minimally invasive surgery should be performed
by a well-trained, highly experienced orthopaedic surgeon. Your orthopaedic surgeon
can talk to you about his or her experience with minimally invasive knee replacement
surgery, and the possible risks and benefits of the techniques for your individual
treatment.

AAOS does not endorse any treatments, procedures, products, or physicians referenced
herein. This information is provided as an educational service and is not intended
to serve as medical advice. Anyone seeking specific orthopaedic advice or assistance
should consult his or her orthopaedic surgeon, or locate one in your area through
the AAOS "Find an Orthopaedist" program on this website.